西双版纳热带雨林树种斜叶榕F. tinctoria水分利用方式的季节变化

Seasonal variation of water use patterns of strangler fig F. tinctoria in the tropical rainforest in Xishuangbanna,SW China

以斜叶榕F.tinctoria为研究对象,通过测定其木质部与其各种潜在水源的氢氧同位素组成,揭示西双版纳地区斜叶榕在不同季节的水分利用变化.结果表明在干热季时的30 cm土壤处水势达到最低值-30.5kPa,在雾凉季时此深度土壤处出现最大水势,为-14.5 kPa,在各个季节70 cm处的土壤水势几乎没有变化.雨季时的土壤含水量比雾凉季与干热季都高(P<0.001),而雾凉季与干热季的土壤含水量则没有显著差异(P=0.64).通过对雨水、雾水、浅层土壤水、深层土壤水、树干腐殖质水及植物木质部水的稳定同位素分析得出,在雨季,雨水与浅层土壤水是斜叶榕的最主要水源;雾凉季时,斜叶榕主要利用土壤水(包括浅层土壤水与深层土壤水).干热季时,浅层土壤水是斜叶榕的最主要水源.因此,斜叶榕的水分利用存在季节变化.

It was tried to reveal the seasonal variation of water use pattern of Ficus tinctoria by a Hydrogen - oxygen stable isotope analysis of its stem xylem water and other potential water sources. The results indicated that the minimum soil water potential was - 30.5 kPa at 30 cm deep in the dry hot season, while the maximum was - 14.5 kPa at 30 cm deep in the foggy season. There was no variation in the soil water potential at 70 cm in depth through all seasons. The soil water content was significantly higher in the rainy season than in the dry hot season and foggy season （ P 〈 0.001 ）, but the difference of the soil water content between the foggy season and the dry hot season was not significant （ P = 0.64）. Therefore, a seasonal variation of water use pattern did exist in different seasons. Rainwater and the water in the shallow soil were the main sources in the rainy season;in the foggy season,the main water source was the soil water （both in the shallow soil and the deep soil） ;and in the dry hot season, the main water source was the water in the shallow soil.